将三元表达式转换为二叉树

// C++ program to convert a ternary expression to// a tree.#include<bits/stdc++.h>using namespace std;// tree structurestruct Node{    char data;    Node *left, *right;};// function create a new nodeNode *newNode(char Data){    Node *new_node = new Node;    new_node->data = Data;    new_node->left = new_node->right = NULL;    return new_node;}// Function to convert Ternary Expression to a Binary// Tree. It return the root of tree//Notice that we pass index i by reference because we want to skip the characters in the subtreeNode *convertExpression(string str, int & i){    // store current character of expression_string     // [ 'a' to 'z']     Node * root =newNode(str[i]);    //If it was last character return    //Base Case    if(i==str.length()-1) return root;    // Move ahead in str     i++;    //If the next character is '?'.Then there will be subtree for the current node    if(str[i]=='?')    {        //skip the '?'        i++;        //construct the left subtree        //Notice after the below recursive call i will point to ':' just before the right child of current node since we pass i by reference        root->left = convertExpression(str,i);                //skip the ':' character        i++;        //construct the right subtree        root->right = convertExpression(str,i);        return root;    }    //If the next character is not '?' no subtree just return it    else return root;}// function print treevoid printTree( Node *root){    if (!root)        return ;    cout << root->data <<" ";    printTree(root->left);    printTree(root->right);}// Driver program to test above functionint main(){    string expression = "a?b?c:d:e";    int i=0;    Node *root = convertExpression(expression, i);    printTree(root) ;    return 0;}

// Java program to convert a ternary // expreesion to a tree.import java.util.Queue;import java.util.LinkedList; // Class to represent Tree node class Node {    char data;    Node left, right;     public Node(char item)     {        data = item;        left = null;        right = null;    }} // Class to convert a ternary expression to a Tree class BinaryTree {    // Function to convert Ternary Expression to a Binary    // Tree. It return the root of tree    Node convertExpression(char[] expression, int i)    {        // Base case        if (i >= expression.length)            return null;             // store current character of expression_string        // [ 'a' to 'z']        Node root = new Node(expression[i]);             // Move ahead in str        ++i;             // if current character of ternary expression is '?'        // then we add next character as a left child of        // current node        if (i < expression.length && expression[i]=='?')            root.left = convertExpression(expression, i+1);             // else we have to add it as a right child of        // current node expression.at(0) == ':'        else if (i < expression.length)            root.right = convertExpression(expression, i+1);             return root;    }        // function print tree    public void printTree( Node root)    {        if (root == null)            return;                        System.out.print(root.data +" ");        printTree(root.left);        printTree(root.right);    }    // Driver program to test above function    public static void main(String args[])     {        String exp = "a?b?c:d:e";        BinaryTree tree = new BinaryTree();        char[] expression=exp.toCharArray();         Node root = tree.convertExpression(expression, 0);        tree.printTree(root) ;    }}/* This code is contributed by Mr. Somesh Awasthi */

# Class to define a node # structure of the treeclass Node:    def __init__(self, key):        self.data = key        self.left = None        self.right = None# Function to convert ternary # expression to a Binary tree# It returns the root node # of the treedef convert_expression(expression, i):    if i >= len(expression):        return None    # Create a new node object    # for the expression at    # ith index    root = Node(expression[i])    i += 1    # if current character of     # ternary expression is '?'    # then we add next character     # as a left child of    # current node    if (i < len(expression) and                 expression[i] is "?"):        root.left = convert_expression(expression, i + 1)            # else we have to add it     # as a right child of    # current node expression[0] == ':'    elif i < len(expression):        root.right = convert_expression(expression, i + 1)    return root# Function to print the tree# in a pre-order traversal patterndef print_tree(root):    if not root:        return    print(root.data, end=' ')    print_tree(root.left)    print_tree(root.right)# Driver Codeif __name__ == "__main__":    string_expression = "a?b?c:d:e"    root_node = convert_expression(string_expression, 0)    print_tree(root_node)# This code is contributed# by Kanav Malhotra

// C# program to convert a ternary // expreesion to a tree. using System;// Class to represent Tree node public class Node{    public char data;    public Node left, right;    public Node(char item)    {        data = item;        left = null;        right = null;    }}// Class to convert a ternary // expression to a Tree public class BinaryTree{    // Function to convert Ternary Expression     // to a Binary Tree. It return the root of tree     public virtual Node convertExpression(char[] expression,                                          int i)    {        // Base case         if (i >= expression.Length)        {            return null;        }        // store current character of         // expression_string [ 'a' to 'z']         Node root = new Node(expression[i]);        // Move ahead in str         ++i;        // if current character of ternary expression         // is '?' then we add next character as a         // left child of current node         if (i < expression.Length && expression[i] == '?')        {            root.left = convertExpression(expression, i + 1);        }        // else we have to add it as a right child         // of current node expression.at(0) == ':'         else if (i < expression.Length)        {            root.right = convertExpression(expression, i + 1);        }        return root;    }    // function print tree     public virtual void printTree(Node root)    {        if (root == null)        {            return;        }        Console.Write(root.data + " ");        printTree(root.left);        printTree(root.right);    }// Driver Codepublic static void Main(string[] args){    string exp = "a?b?c:d:e";    BinaryTree tree = new BinaryTree();    char[] expression = exp.ToCharArray();    Node root = tree.convertExpression(expression, 0);    tree.printTree(root);}}// This code is contributed by Shrikant13

<script> // Javascript program to convert a ternary // expreesion to a tree. // Class to represent Tree node class Node{    constructor(item)    {        this.data = item;        this.left = null;        this.right = null;    }}// Function to convert Ternary Expression // to a Binary Tree. It return the root of tree function convertExpression(expression, i){        // Base case     if (i >= expression.length)    {        return null;    }        // Store current character of     // expression_string [ 'a' to 'z']     var root = new Node(expression[i]);        // Move ahead in str     ++i;        // If current character of ternary expression     // is '?' then we add next character as a     // left child of current node     if (i < expression.length && expression[i] == '?')    {        root.left = convertExpression(expression, i + 1);    }        // Else we have to add it as a right child     // of current node expression.at(0) == ':'     else if (i < expression.length)    {        root.right = convertExpression(expression, i + 1);    }    return root;}// Function print tree function printTree(root){    if (root == null)    {        return;    }    document.write(root.data + " ");    printTree(root.left);    printTree(root.right);}// Driver codevar exp = "a?b?c:d:e";var expression = exp.split('');var root = convertExpression(expression, 0);printTree(root);// This code is contributed by noob2000</script>